Low Pressure Fuel Management and Delivery System for a Liquefied Natural Gas Rail Locomotive Tender

Abstract

A low-pressure fuel management and delivery system 10 for a liquefied natural gas (LNG) rail tender is disclosed. The system provides a rail tender that is inherently safer in operation to known LNG rail tenders through its use of a double-hulled tank design 12, which lacks any penetration of the bottom surface of the first inner tank 16 by any portion of the fuel supply portion of the system 10; the lower pressure storage of the fuel 22 in the first inner tank 16; the inclusion of a gas return line 58 for directing fuel 22 trapped in the LNG flow lines 38, the heat exchanger 46, or the multistage gas compressor 52 to the vapor space 32 of the first inner tank 16 at safe pressures and temperatures; the lack of cryogenic pumps within the first inner tank 16 to drive the fuel supply portion of the system 10; and the location of all the flow controlling valves 40, 42, 50, and 56 in positions that afford them improved physical protection from potential damage due to vehicular collisions or other railroad accidents. During operation, the fuel management and delivery system 10 provides required fuel flow rates and temperatures to an associated locomotive through the use of hydrostatic pressure differences between the LNG fuel 22 and the vapor space 32 within first inner tank 16, as well as a heat exchanger 46 and a multi-stage compressor 52, which are preferably located external of the double-hulled fuel storage tank 12, but on the same rolling stock chassis 14.

Description

FIELD OF THE DISCLOSURE[0001]The invention relates in general to a fuel management and delivery system. More particularly, the present invention relates to a fuel management and delivery system for a locomotive tender. More precisely, the invention relates to a liquefied natural gas fuel management and delivery system for a locomotive tender suitable for operating at low positive gage pressures or near-atmospheric pressures.BACKGROUND OF THE DISCLOSURE[0002]While rail moves only sixteen percent of freight by weight in the United States, it is the second most used means of transportation for freight, and by far its most efficient mode of transportation. With the growing concerns of the environmental impacts due to the burning of fossil fuels and transportation sector occupying the second place on the list of industries that contribute the most to the United States' annual greenhouse gas emissions, railroads are seeking, legislators are demanding, and regulators have established requi...

AI Technical Summary

Benefits of technology

[0007]An embodiment of the present invention provides a fuel management and delivery system that may supply liquefied natural gas (LNG) fuel from a rail tender to a locomotive at or near atmospheric pressures without requiring submerged, internal cryogenic pumps or penetration of the bottom of the tender's inner LNG tank.

[0009]The doubled-hulled, pressurized LNG tank includes a first inner tank and a second outer tank. The first inner tank is generally made of stainless steel, but can be made of any other material suitable to maintain the liquefied natural gas at temperatures at or below 111 K (−260° F.), while ensuring the required structural rigidity and strength needed for safe operation. The second outer tank is generally constructed of carbon steel to provide a protective envelope for the first inner tank and to maintain a near vacuum condition in the annular volume space between the inner and outer tanks. In addition, the purpose of the outer tank is to provide additional protection against damage to the inner tank in the event of an accident that would otherwise damage the first inner tank. The annular space between the first inner tank and the second outer tank is maintained at or near vacuum and filled with insulative materials for maintaining the first inner tank at or below a desired temperature. Further, the annular space may include various elements of the fuel management and delivery system.

Problems solved by technology

While natural gas is a potential solution to many of the present problems related to the continued use of coal, diesel fuel, or other hydrocarbon based fuel sources, the carriage of LNG in tenders comes with its own challenges, not the least of which is safety.

The higher the tender tank pressure the greater is the potential hazard area, if LNG is released from the tender due to an accident.

Fixing pump failures and maintenance of a pump submerged in a very cold (111 K [−260° F.]) liquid pose technical and cost challenges.

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